Studies of multi-type composite energy storage for the photovoltaic generation system in a micro-grid

Distributed generation (DG) that uses renewable energy sources (such as solar and wind) has an unstable output and this can negatively affect existing electric power systems. In order to reduce above impact, we need to control the output through individual DG installed in a micro-grid. This Paper designs a grid-connected Photovoltaic (PV) system based on the multi-type composite energy storage. First, this paper introduces the operation principle of the various parts as well with the control strategy of the power flow. Then, it describes the model of PV generation system. Finally it uses the battery and the super-capacitor as the multi-type composite energy storage device and designs the charge-discharge control strategy according to its characteristics. This paper verifies the feasibility of the energy storage control strategy through the simulation models which is built based on the PSCAD/EMTDC platform. Analyzing the control strategy simulation of different power flow model, it verifies the correctness and rationality of proposed multi-type composite energy storage scheme in order to regulate power balance appropriately.